The semiconductor industry has a need to access many electronic devices on a semiconductor wafer. As the semiconductor industry grows and devices become more complex, many electrical devices, most commonly semiconductor devices, must be electrically tested, for example, for leakage currents and extremely low operating currents. These currents are often below 100 fA. In addition, the currents and device characteristics are often required to be evaluated over a wide temperature range to understand how temperature affects a device. Also, because of materials characteristics of dielectrics, it is often difficult to test characteristics of semiconductor devices in a wide operating temperature range.
To effectively measure at currents below 100 fA (Femto Ampere), a measurement signal must be isolated from external electrical interference, leakage currents through the dielectric material, parasitic capacitance, triboelectric noise, piezoelectric noise, and dielectric absorption, etc.
Accordingly, there is a need for improved semiconductor test equipment for electrically probing semiconductor devices at low currents over a wide temperature range.